Steam-valve



J. D. WILSON. Steam-Valve.

No. 226,218. Patented April 6, 1880.-

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SPECIFICATION forming part of Letters Patent No. 226,218, dated April 6,1880.

Application filed November 4, 1879.

To all whom it may concern Be it known that I, JAMES D. WILsoN, ofMontague, in the county of Muskegon and tate of Michigan, have inventedan Improvement in Steam-Chests, of which the following is aspecification.

The nature of my invention relates to certain new and usefulimprovements in the construction of steam-valves, by means of which agreat saving of steam is obtained where only a portion of the stroke ofthe engine to which the valve is attached is required, as is the case incircular-saw mills, where the carriage, which usually has a travel ofabout thirty feet, is attached to and driven by a steam-engine of a likelength of cylinder, and the mill is ordinarily employed in sawing twelveto sixteen feet logs. In such case the piston travels but about half thelength of the stroke, and consequently there is a great waste of steamin using steam chests and valves of the known constructions.

The objectof my invention is to prevent this waste and utilize theexhaust-steam to fill the cylinder behind the piston on the unutilizedportion of the stroke before the live steam is let in to compel thereturn-stroke of the piston.

The invention consists in the peculiar construction of parts and theircombination, as more fully hereinafter described.

Figure 1 is a vertical central section of the steam chest and valve infull. Fig. 2 is a vertical section central of the steam chest and valve.Fig. 3 is a cross-section of the piston-valve on the line as :0 in Fig.2.

In the accompanying drawings, which form apart of the specification, Arepresents a St6tI11Gl16St, provided with a steam-inlet, a, an outlet orexhaust, b, and steam-passages c 0, leading to each end of the cylinderof the engine to which steam-chest is attached.

B is a piston-valve, upon which there is cut an annular recess, 0,midway between the ends of the piston, and having small ports f leadingfrom said recess to the full portion of the piston.

g is a chamber through the longitudinal center of the piston,terminating at each end in the lateral openings 6 near the ends of thepiston.

The steam-passages c c and a are continued all around the inside of thechest, and form the bridges it between them.

0 is the valve-stem, which is designed to be worked by a handlever.

As the valve is moved forward or back the steam will pass from one endof the cylinder over one of the bridges through successively thesteam-passages c, i, g, and a into the opposite end of the cylinder.When the valve is reversed the direction of the steam also is reversed,and will fill the other end of the cylinder and react upon the pistonbefore live steam is admitted, thereby saving that amount of steamrequired to fill that space. When sufficient exhaust-steam has beenadmitted the valve is moved to the position shown in Fig. 1, when theremainder of the exhaust-steam passes direct to the exhaustport andlivesteam passes to the cylinder, as shown by the arrows in Fig. l.

The small ports f, in the edges of the recess in the piston, serve toadmit the steam easier and more gradually and enable the operator tocontrol the speed of the carriage as desired.

It will be observed that the smaller recesses f in the edge of the largerecess are equal on both edges of the said recess, and are all equallyopen to live steam, so as to perfectly balance the pressure on the valvewhen traveling over the bridges h, and that there is a single passagethrough the valve which is in direct communication with the ports 0 0,so that there is not the slightest chance for a difference in thepressure on opposite sides of the valve, whereas in that form of valvewherein there are several distinct openings the pressure varies ondifferent parts of the circumference of the valve, owing to the tortuouscourse the steam has to pursue to get into some of the chambers and theease with which it enters into the others.

By my construction, therefore, a valve is produced that is perfectlybalanced, and is thus easily moved and controlled by hand.

Vhat I claim as my invention, and desire 5 to secure by Letters Patent,is

The piston-valve herein described, provided with a single centralchamber, g, communicating with the ports 0 c by the lateral openingsi i,and having one or more sets of re cesses facing each other and adaptedto 00111- 10 municate with the feed-port a, in combination with asteam-chest having the ports a, b c and bridges h h, all constructed andarranged substantially as herein shown and described.

JAMES D. WILSON. Witnesses:

MALCOLM HENDRIG, HENRY DOUVILLE.

